Stephenson County

Every recorded tornado

1. Injuries and deaths are for the tornado’s whole path, which may extend beyond the county. Deaths recorded within Stephenson County: 0.
2. Weak tornadoes were under-recorded before Doppler radar coverage became national in the early 1990s, so earlier decades read low. Ratings use the Fujita scale before February 2007 and the Enhanced Fujita scale after.

Storm Prediction Center severe weather database, 1950 to 2025.

Smoke overhead

1. A smoke day is a date on which a smoke plume traced by NOAA Hazard Mapping System analysts from satellite imagery covered this place's point (the county's population centre or the city centre). Counts here are of medium or heavy smoke. Since 2018 analysts have often drawn light smoke as one area over most of the continent, so light-smoke counts are not comparable from year to year. The plumes show smoke anywhere in the air above, not air quality at the ground, and smoke hidden by cloud is missed.

NOAA Hazard Mapping System smoke analysis, 2011 to 2026, retrieved October 30, 2026.

Claims by ZIP code

This product uses the Federal Emergency Management Agency's OpenFEMA API, but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).

OpenFEMA NFIP Redacted Claims v3, refreshed August 4, 2026. NOAA Storm Events through 2026.

River crests

River gauges

1. Crests are the highest and the recent crests the National Weather Service lists for each river gauge in the county that has a flood stage, not every flood. Flood categories use each gauge's current flood stages; crests from before levees, dams or channel changes may not be comparable. Crests measured on an old datum are left out of the rankings.

NOAA National Water Prediction Service gauge records, retrieved October 30, 2026.

1. The Palmer Drought Severity Index is computed by NOAA each month from the county's average temperature and precipitation, relative to the county's own climate. Zero is normal; -3 or lower is severe drought and -4 or lower extreme drought. It describes the long-term balance of moisture, not water supply or crop losses.

NOAA NCEI nClimDiv county Palmer Drought Severity Index, 1895 to September 2026, issued October 6, 2026.

Every earthquake of magnitude 4 or more within 50 miles

1. Earthquakes of magnitude 2.5 or more in the USGS Comprehensive Catalog since 1900. Within 50 miles means the epicentre lies within 50 miles of the county boundary (or inside the county).
2. Small earthquakes were under-recorded before the modern seismic networks of the 1970s and are still missed in remote areas, so early decades read low. Magnitudes are as the catalogue reports them and mix scales (moment, local and body-wave).

USGS ANSS Comprehensive Earthquake Catalog, 1900 to present, retrieved October 30, 2026.

More event types since 1996

Costliest events since 1996

1. Jul 22, 2017Flood$7.0 million
   National Weather Service narrative

   Heavy rainfall of 3 to over 12 inches over significant areas from 20 to 22 July in southern Wisconsin and Northern Illinois moved downstream causing the Rock River to rise well above major flood stage levels just downstream of Freeport down to the Mississippi at Moline. ||Freeport rose just below major flood stage level of 16.0 feet on July 23rd, 2017 at approximately 645 AM CST. It crested around 15.9 feet at approximately 10 AM CST on July 23rd, 2017 and fell below 15.5 feet at approximately 815 PM CST on July 25th.||Widespread river flooding and flash flooding resulted in a preliminary estimation of 7 to 8 million dollars in damage.

2. Jul 5, 2003Thunderstorm Wind$2.5 million
   National Weather Service narrative

   A MCS thunderstorm complex bowed out and raced across Eastern Iowa and Northwest Illinois in the pre dawn hours. Due to high freezing levels, hail was minimal. Along the Highway 20 corridor in Northeast Iowa and Northwest Illinois winds were estimated at 60 to 70 knots in places (70-80 mph). The cities of Dubuque, Iowa and Freeport, Illinois were particularly hard hit with many trees downed or uprooted. In Stephenson County Illinois, a well defined path of straight line winds was noted from 5 miles West of Freeport, across the northern part of the city, and east to the Stephenson/Winnebago county line. On the US 20 bypass around Freeport at Jct IL 75 five (5) 90 foot high voltage…

3. May 9, 2003High Wind, Stephenson$2.0 million
   National Weather Service narrative

   Thunderstorms developed north of a warm front in Missouri and raced northeast on a strong low level jet. A gravity wave developed off the thunderstorms in Eastern Iowa and Northwest Illinois and produced a concentrated band of high winds across Stephenson County Illinois. Official observation sites did not show this narrow band of high winds, but several home weather stations reported winds gusting over 55 mph before power was lost. The heaviest damage was in a 0.5 to 1 mile wide band running from about 2 miles south of Loran, Illinois to Freeport, Illinois. Numerous trees and power lines were downed with power poles snapped in half. A final report from Stephenson County Illinois…

4. Apr 19, 1996Thunderstorm Wind$1.2 million
   National Weather Service narrative

   Wind damage was done to several grain bins and power lines were downed. 11 buildings were damaged or destroyed in a 2 mile radius of Pearl City, Illinois. There were no human injuries; however, 8 cattle were killed by flying debris. Severe winds were sustained for several minutes in the Pearl City, Illinois area and remained above severe limits into Freeport, Illinois.

5. May 4, 2003High Wind, Stephenson$1.0 million
   National Weather Service narrative

   numerous reports of limbs & power lines down

6. Jul 22, 2010Flash Flood$1.0 million
   National Weather Service narrative

   Heavy rains of 2.5 to 6 inches fell across Stephenson County the evening hours of July 22 and through the morning of July 23 resulting in flash flooding of much of the county. At 1248 am CDT, Freeport was flooded with about 10 inches of water in the streets. Several roads were completely covered with water, especially in the vicinity of the Taylor Park District and near Route 75. The flood waters came up to the middle of car tires. Just before 130 am CDT, WREX TV relayed a report from a Freeport viewer that there was standing water everywhere. At 405 am CDT, several homes in Pearl City were flooded. Some of the residences on the north side of town had flood waters up to the first…

7. Jul 24, 2010Flood$500,000
   National Weather Service narrative

   Heavy rains during the fourth week of July resulted in the Pecatonica River at Freeport going above the moderate flood stage level of 14 feet around 3 am CDT July 24. It crested around 16.2 feet around 1 am CDT July 25. It fell below the moderate flood stage level around 10 pm CDT July 28.

8. Jul 24, 2010Flash Flood$500,000
   National Weather Service narrative

   Heavy rains of about 3 inches in under 3 hours (for a total of about 11 inches in less than 32 hours) resulted in extensive flash flooding during the morning of July 24. The greatest impact was flash flooding of Yellow Creek from Pearl City to Freeport, with additional impacts from flash flooding of the Pecatonica River in and near Freeport. ||Local emergency management officials described the flood damage as the worst damage I've seen in 19 years, and many lifelong residents affected by Yellow Creek described it as worse than anything they had ever experienced in their lifetimes. ||Forty-three roads in Stephenson County were under water and closed to traffic, including Business…

9. Jul 27, 2011Flash Flood$500,000
   National Weather Service narrative

   Torrential rains of 3 to 8 inches caused some flash flooding across parts of Stephenson County during the evening of July 27 and morning of July 28. There were reports of cattle scattered through county by flood waters with some washed downstream. The flood waters were several feet deep in the town of Pearl City. Two people died just west of Freeport, IL from carbon monoxide fumes from a generator use to pump water from a flooded basement.

10. Aug 4, 2008Thunderstorm Wind$250,000
    National Weather Service narrative

    Wind gusts estimated to be 65 to 75 mph caused widespread tree and structural damage in the vicinity of Freeport, IL between 630 pm and 655 pm August 4. On Rock City Rd, several trees and branches were blown down as well as a metal storage shed. In addition, twenty-five rows of corn on both sides of the road were flattened. Some buildings on the southwest side of town were damaged. On Fairview Rd, a tree was blown over onto a house. On Edwardsville Rd, some large tree limbs were blown down. A power outage was also observed across the county.

1. Storm Events records before 1996 cover only tornadoes, thunderstorm wind and hail. Damage figures are as reported by the National Weather Service at the time, not adjusted for inflation.

NOAA NCEI Storm Events Database, 1950 to 2026, issued October 26, 2026.

All-time high

103°FJul 8, 2012

All-time low

−31°F2 times, most recently Feb 1, 2019

Warmest night

78°F2 times, most recently Jul 20, 2019

Coldest day

−15°FFeb 3, 1996

Wettest day

9.12 inAug 21, 2002

Snowiest day

11.0 inFeb 2, 2011

Hottest year

2012mean 51.8°F

Coldest year

1996mean 44.5°F

Wettest year

201953.58 in

Driest year

198921.19 in

Snowiest season

70.4 in1978-79

Station Freeport Wwtp (USC00113262), 750 ft elevation, 2.8 miles from the population centre. Daily records from 1973 to October 27, 2026; 98.5% of days in the last 30 years are complete. Records at a single station can differ from a city’s official threaded record, which may combine several stations.

NOAA NCEI Global Historical Climatology Network Daily.

This product uses the Federal Emergency Management Agency's OpenFEMA API, but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).

OpenFEMA Disaster Declarations Summaries, retrieved October 30, 2026. Statewide declarations are not listed.

Neighbouring counties

• Tornadoes NOAA Storm Prediction Center severe weather database, through 2025.
• Tropical cyclones NOAA National Hurricane Center HURDAT2 (Atlantic; Northeast and Central Pacific), through 2025.
• Wildfire USGS/USFS Monitoring Trends in Burn Severity, through 2026.
• Storm events NOAA NCEI Storm Events Database, through 2026.
• Flood insurance OpenFEMA NFIP Redacted Claims v3, refreshed August 4, 2026.
• Declarations OpenFEMA Disaster Declarations Summaries v2, retrieved October 30, 2026.
• Weather records NOAA NCEI Global Historical Climatology Network Daily, station USC00113262.
• River crests NOAA National Weather Service, National Water Prediction Service river gauges, retrieved October 30, 2026.
• Drought NOAA NCEI nClimDiv county Palmer Drought Severity Index, through September 2026.
• Smoke NOAA NESDIS Hazard Mapping System smoke analysis, retrieved October 30, 2026.
• Earthquakes USGS ANSS Comprehensive Earthquake Catalog (ComCat), retrieved October 30, 2026.

Joins, thresholds and known limits are set out in the methodology. Found an error? Report it. Page built October 30, 2026.